ABO3 perovskite material comprising sn at a-site and method for preparing same

Abstract

The present invention provides a method for preparing a stable ABO3 perovskite material containing divalent Sn at the A-site and a perovskite compound obtained by the preparation method. The present invention is characterized by preparation using a mist chemical vapor deposition method and, compared with the prior art, can provide advantages, such as a large band gap and excellent light transmittance, through Sn2+ ion with high stability present at the A-site.

Description

Perovskite ABO3 material containing SN at A site and method for producing same

[0001] The present invention relates to a novel perovskite material applicable to the field of semiconductor thin films promising for use as transparent semiconductors or power semiconductors, and more specifically, to a perovskite material having an ABO3 structure stably containing Sn at the A site of the perovskite material represented by ABO3, and a method for producing the same.

[0002] Referring to Figure 1, perovskite is a material with the general chemical formula ABX3, where two types of cations A and B and one type of anion X combine to form a three-dimensional crystal. Perovskite can be divided into oxide and halide perovskite materials depending on the element at the X site. When the X site element is oxygen, it is called perovskite oxide, and is generally expressed as ABO3.

[0003] Recently, research on stannate materials in which tin (Sn) occupies the B site has been actively conducted, and transparent semiconductor properties in solid solutions of materials such as BaSnO3, SrSnO3, and CaSnO3 are attracting attention. Stannate semiconductors can transmit not only visible light but also UV light due to their wide bandgap of 3.5 to 4.6 eV, and also have a very high charge mobility (320 cm in a single crystal) compared to other oxide semiconductors such as SrTiO3 because the conduction band is composed of the s-orbital of Sn. 2 / Vs) has the advantage of having.

[0004] Meanwhile, Sn is a tetravalent cation (Sn 4+ ) can exist as a divalent cation (Sn 2+ ) can also exist. However, the prior art is Sn2+ Due to its instability, Sn was rarely used as an element at the A site, but only as an element at the B site. Sn is used as an element at the A site of perovskite oxides such as BaTiO3, SrTiO3, BaZrO3, and BaHfO3. 2+ A paper using ["Synthesis and stability of Sn(II)-containing perovskites: (Ba,Sn II )Hf I VO3versus (Ba,Sn II )Sn I VO3", Journal of Solid State Chemistry Volume 302, October 2021, 122419], the synthesized material was very unstable and could only be partially substituted at the A site, and in 2022, Sn was synthesized by ion exchange method in SnHfO3 nanoshells. 2+ A paper was published that occupied the entire A site, but it was synthesized in a highly metastable state.

[0005] Sn so far 2+ Stable perovskite oxides in which ions stably occupy the A site completely have not been discovered. Although SnTiO3 thin films have been reported ("Structural and Dielectric Properties of SnTiO3, a Putative Ferroelectric", Crystal Growth & Design Volume 11, April 2011, 1422), they have an ilmenite structure, not a perovskite structure.

[0006] One object of the present invention is to provide a method for producing a stable perovskite ABO3 material containing divalent Sn at the A site.

[0007] Another object of the present invention is to provide Sn at site A. 2+To provide a stable perovskite compound including the same and a semiconductor including the same.

[0008] A method for producing a stable perovskite ABO3 material containing divalent Sn at the A site for one purpose of the present invention is characterized in that it is produced on a substrate through a mist chemical vapor deposition (MCVD) method of an acidic aqueous solution containing Sn ions. Specifically, it includes a first step of generating a mist by dropletizing a raw material solution, and a second step of spraying and depositing the mist on a substrate to form a thin film.

[0009] The raw material solution is an acidic aqueous solution containing Sn ions, and may be a solution prepared by mixing an acidic aqueous solution with any one Sn precursor aqueous solution selected from SnCl2 or SnCl4. Here, the acidic aqueous solution may be HCl.

[0010] In one embodiment, the raw material solution of the present invention may be a solution containing SnCl2 and HCl, or a solution containing SnCl4 and HCl. When using such a solution, Sn is added to each of the A and B sites. 2+ and Sn 4+ It is possible to manufacture SnSnO3 perovskite with stable positioning. SnSnO3 perovskite has the characteristics of a wide bandgap semiconductor with a large bandgap of approximately 5.0 eV but at the same time, it can realize an electrical conductivity of over 100 S / cm. Such materials can be utilized in various applications such as transparent conductive films, wide bandgap transistors, sensors, catalysts, and electrodes.

[0011] In another embodiment, the raw material solution of the present invention may be a solution containing a material containing a metal ion to be positioned at a tetravalent B site, SnCl2, and HCl, or a solution containing a material containing a metal ion to be positioned at a tetravalent B site, SnCl4, and HCl. In one embodiment, the material containing a metal ion to be positioned at a B site may be a material containing one or more metal ions of Ti, Sn, Pt, Ce, Pb, Mg, and Hf. In this case, a perovskite material may be obtained in which Sn is substituted at the A site and one or more metal ions of Ti, Sn, Pt, Ce, Pb, Mg, and Hf are substituted at the B site.

[0012] The substrate may be any type of substrate known in the industry, and the present invention does not specifically limit the type of substrate. In one embodiment, the substrate may be a sapphire substrate.

[0013] In the first step, droplet formation can be accomplished using an ultrasonic transducer. The ultrasonic transducer, placed within the raw material solution, vibrates the raw material solution, producing a mist. The produced mist can then be transported to the space where the substrate is placed, using air or another carrier gas, to perform the second step.

[0014] The second step is characterized by performing the mist at a temperature where the Leidenfrost effect occurs. The Leidenfrost effect is a phenomenon in which, when a liquid comes into contact with an object at a temperature much higher than its boiling point, a vapor film instantly forms, protecting the liquid from heat transfer. In the present invention, performing the process at a temperature where the Leidenfrost effect occurs enables rapid diffusion and movement of the raw material on the substrate surface, thereby enabling rapid thin film growth.

[0015] Preferably, the second step can be performed at a temperature of 100°C or higher, preferably 300°C or higher, and more preferably 500°C or higher, at which the Leidenfrost effect occurs. The spraying time can be 1 to 60 minutes, but the present invention is not necessarily limited thereto.

[0016] At this time, the substrate in the second step may be tilted at a certain angle. This is because the angle at which the substrate is placed can affect the deposition. Using a substrate at a desirable angle allows for highly uniform and stable deposition.

[0017] The present invention can additionally perform a third step of heat-treating the substrate on which the perovskite thin film is formed at a high temperature after the second step. The perovskite thin film manufactured through the manufacturing method of the present invention is very stable, so its structure is not destroyed even during the heat treatment. The crystallinity of the perovskite material can be increased due to crystallization and grain growth and alignment caused by the supply of thermal energy during the heat treatment process. Preferably, the heat treatment temperature can be performed at about 500°C or higher, and the heat treatment time can be 90 to 150 minutes.

[0018] Referring to FIG. 2, a perovskite compound for another purpose of the present invention includes a perovskite compound represented by the following chemical formula 1.

[0019] [Chemical Formula 1]

[0020] ABO3

[0021] A is a divalent cation Sn or one or more metal ions selected from a divalent cation metal other than the divalent cation Sn,

[0022] B is one or more metal ions selected from tetravalent cation metals.

[0023] The cationic metal that can be substituted for A may be a divalent cationic metal. For example, Sn 2+The divalent cation metal ion other than B may be any one ion selected from the group consisting of Ba2+, Sr2+, Ca2+, Zn2+, Mg2+, Pb2+, etc., and the tetravalent cation metal ion forming B may be Sn 4+ , Ti 4+ , Pt 4+ , Ce 4+ , Pb 4+ , Mg 4+ , Zr 4+ and Hf 4+ It may be one or more ions selected from the group consisting of .

[0024] In addition, A or B of the perovskite compound may be doped with one or more metal ions having an oxidation number between 1+ and 5+ as n-type or p-type. The ABO3 perovskite oxide in which Sn2+ occupies A may have some of the A and B sites replaced by metal ions having an oxidation number between 1+ and 5+. For example, (Sn 2+ 0.99 La 3+ 0.01 )SnO3, Sn doped with Nb5+ at B site 2+ (Sn 4+ 0.99 Nb 5+ 0.01) Materials such as O3 are possible, and simultaneous doping of A and B sites is also possible.

[0025] In one embodiment, the perovskite compound may be a perovskite compound represented by SnSnO3. The SnSnO3 perovskite compound is characterized by a band gap of 5.0 eV and an optical transmittance of greater than 70% in the UV region at a wavelength of 300 nm.

[0026] According to the present invention, Sn at site A 2+ Sn with stably arranged ions 2+BO3 perovskite oxide can be provided, and this perovskite oxide has the advantage of being highly stable and maintaining its structure even when heat-treated at high temperatures, making it highly useful in the semiconductor field.

[0027] Figure 1 is a schematic diagram of the crystal structure of SrTiO3, a representative ABO3-type perovskite oxide.

[0028] FIG. 2 is a graph showing (a) the crystal structure of SnSnO3 perovskite oxide according to Example 2 of the present invention and (b) the X-ray diffraction analysis results confirming that the material is epitaxially aligned and grows into a thin film when deposited on a sapphire (Al2O3) substrate.

[0029] Figure 3 is Sn according to Example 1 of the present invention. 2+ Sn 4+ This is an electron microscope image showing a cross-section of an O3 perovskite oxide thin film.

[0030] Figure 4 is Sn according to Example 2 of the present invention. 2+ Sn 4+ It shows the bandgap of O3 perovskite oxide thin film.

[0031] Figure 5 is Sn according to Example 1 of the present invention. 2+ Sn 4+ It shows the transmittance of O3 perovskite oxide thin film.

[0032] Figure 6 is Sn according to Example 1 of the present invention. 2+ Sn 4+ XRD measurement results before and after stability tests of O3 perovskite oxide thin films are shown.

[0033] Hereinafter, embodiments of the present invention will be described in detail with reference to the attached drawings. The present invention is susceptible to various modifications and variations, and thus specific embodiments are illustrated in the drawings and described in detail in the text. However, this is not intended to limit the present invention to a specific disclosed form, but rather to encompass all modifications, equivalents, and alternatives falling within the spirit and technical scope of the present invention. Throughout the description of each drawing, similar reference numerals have been used to designate similar components.

[0034] The terminology used in this application is only used to describe specific embodiments and is not intended to limit the present invention. The singular expression includes the plural expression unless the context clearly indicates otherwise. In this application, it should be understood that the terms "comprise" or "have" indicate the presence of a feature, step, operation, component, part, or combination thereof described in the specification, but do not preclude the possibility of the presence or addition of one or more other features, steps, operations, components, parts, or combinations thereof.

[0035] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. Terms defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology, and will not be interpreted in an idealized or overly formal sense unless explicitly defined herein.

[0036] Example 1: Sn using SnCl2 as a precursor 2+ Sn 4+ O3 thin film deposition

[0037] In this embodiment, Sn is formed using a mist chemical vapor deposition method. 2+ Sn 4+ O3 thin films were deposited. To prepare the precursor, tin(II) chloride dihydrate (SnCl2·2H2O, Sigma Aldrich) was dissolved in water (DI water) at concentrations of 0.005 M, 0.025 M, and 0.05 M, and hydrochloric acid at a concentration of 0.8 M was added to this solution.

[0038] Then, mist was generated from the precursor solution using an ultrasonic transducer (2.4 MHz). The generated mist was introduced into the reaction chamber where the substrate was placed together with a carrier gas (air, 5 L / min). A horizontal tube furnace using a quartz tube was used as the reaction chamber. A c-plane α-Al2O3 substrate was placed on a graphite susceptor with a substrate inclination angle of 45°, and a thin film was deposited at a temperature of 500°C for 3 minutes.

[0039]

[0040] Example 2: Sn using SnCl4 as a precursor 2+ Sn 4+ O3 thin film deposition

[0041] In this embodiment, Sn is formed using a mist chemical vapor deposition method. 2+ Sn 4+ O3 thin films were deposited. To prepare the precursor, tin(IV) chloride pentahydrate (SnCl4·5H2O, Sigma Aldrich) was dissolved in water at a concentration of 0.05 M, and hydrochloric acid was added to the solution at concentrations of 0, 0.4, 0.8, and 1.6 M, respectively.

[0042] Then, mist was generated from the precursor solution using an ultrasonic transducer (2.4 MHz). The generated mist was introduced into the reaction chamber where the substrate was placed together with a carrier gas (air, 5 L / min). The reaction chamber was a horizontal tube furnace using a quartz tube. A c-plane α-Al2O3 substrate was placed on a graphite susceptor with a substrate inclination angle of 45°, and a thin film was deposited at a temperature of 500°C for 3 minutes.

[0043] Experimental example

[0044] FIG. 2 is a graph showing (a) the crystal structure of SnSnO3 perovskite oxide according to Example 2 of the present invention and (b) the X-ray diffraction analysis results confirming that the material is epitaxially aligned and grows into a thin film when deposited on a sapphire (Al2O3) substrate.

[0045] Referring to Fig. 2, the pattern of X-ray diffraction analysis (θ-2θscan) in the thickness direction (vertical; out-of-plane) of the SnSnO3 thin film grown on the sapphire substrate confirms that the lattices are well aligned in one direction. The peaks of the thin film measured in the analysis matched the diffraction peaks (Bragg diffraction peaks) due to the ABO3 type perovskite crystal structure having divalent and tetravalent Sn at the A-site and B-site, respectively, and the SnSnO3 crystal planes are marked in the figure. In addition, in order to confirm the three-dimensional structural orientation of the thin film, the results of φ-scan, which measured while rotating the sample 360 ​​degrees about the crystal plane (horizontal; in-plane crystal plane) tilted with respect to the growth axis of the thin film, indicate that this thin film is an epitaxial thin film that is three-dimensionally aligned along the lattice of the sapphire substrate in the horizontal direction as well.

[0046] Figure 3 is a scanning electron microscope (SEM, left) and transmission electron microscope (TEM, right) image taken by cutting a cross-section after depositing a SnSnO3 thin film on an Al2O3 substrate using a mist method according to Example 1 of the present invention.

[0047] Referring to Fig. 3, it can be confirmed that the interface between the substrate and the thin film is clean and the grid arrangement is well aligned perpendicular to the substrate direction.

[0048] Figure 4 is Sn according to Example 2 of the present invention. 2+ Sn 4+ It shows the bandgap of O3 perovskite oxide thin film.

[0049] Referring to Fig. 4, Sn deposited on an Al2O3 substrate 2+ Sn 4+ It can be confirmed that the bandgap of the O3 perovskite oxide thin film has a value near 5.0 eV. This figure shows that the bandgap of SnSnO3 is close to that of BaSnO3 (Ba 2+ ionic radius = 1.61 Å, 3.2 eV), SrSnO3 (Sr 2+ ionic radius = 1.44 Å, 4.3 eV), CaSnO3 (Ca 2+ It shows that the bandgap of Sn has a larger value than that of the ionic radius of the ion occupying the A-site (1.34 Å, 4.6 eV), which is in good agreement with the tendency for the bandgap to increase as the ionic radius of the ion occupying the A-site decreases (Sn 2+ ionic radius: 1.18 Å).

[0050] Figure 5 is Sn according to Example 2 of the present invention. 2+ Sn 4+ It shows the transmittance of O3 perovskite oxide thin film.

[0051] Referring to Figure 5, it is confirmed that the transmittance is 70% or more in the wavelength range of 200 nm, which is the ultraviolet (UV) region. Therefore, the Sn 2+ Sn 4+O3 perovskite oxide thin films are shown to be wide bandgap semiconductor materials that can utilize electrical properties while transmitting UV wavelengths.

[0052] Table 1 below shows Sn according to Example 2 of the present invention. 2+ Sn 4+ The results of measuring the charge concentration, charge mobility, and electrical conductivity of O3 perovskite oxide thin films are presented.

[0053] [Table 1]

[0054]

[0055] Referring to Table 1, Sn deposited according to the example of Example 2 2+ Sn 4+ The charge concentration of O3 perovskite oxide thin film is 10 20 / cm 3 Above, the charge mobility is 10 cm 2 / Vs or more, and the electrical conductivity is 10 S / cm or more, which means that this material can be used as a wide bandgap semiconductor.

[0056] Sn manufactured according to Example 1 of the present invention 2+ Sn 4+ Sn was deposited using mist chemical vapor deposition method to test the stability of O3 thin film. 2+ Sn 4+ O3 thin films were heat-treated in air using a horizontal tubular furnace. Stability was confirmed through XRD analysis before and after heat treatment, and the results are shown in Figure 7.

[0057] Referring to Figure 6, there is no change in the peaks indicating crystallinity and orientation direction before and after heat treatment, as shown in the figure. From this, it can be confirmed that the SnSnO3 thin film produced by the proposed invention is structurally stable.

[0058] Although the present invention has been described above with reference to preferred embodiments thereof, it will be understood by those skilled in the art that various modifications and changes may be made to the present invention without departing from the spirit and scope of the present invention as set forth in the claims below.

Claims

1. Including mist chemical vapor deposition (mist-CVD) of an acidic aqueous solution containing Sn ions on a substrate. A method for producing a stable perovskite material ABO3 containing two valent Sn atoms at the A site.

2. In paragraph 1, The above mist chemical vapor deposition includes depositing the aqueous solution at a temperature at which Leidenfrost occurs on the substrate to be deposited. A method for producing a stable perovskite material ABO3 containing two valent Sn atoms at the A site.

3. In paragraph 2, The temperature of the above mist chemical vapor deposition is 300℃ or higher. A method for producing a stable perovskite material ABO3 containing two valent Sn atoms at the A site.

4. In paragraph 2, The above aqueous solution is characterized in that it is an aqueous solution of SnCl2 or SnCl4. A method for producing a stable perovskite material ABO3 containing two valent Sn atoms at the A site.

5. In paragraph 4, The above aqueous solution is characterized in that it contains HCl. A method for producing a stable perovskite material ABO3 containing two valent Sn atoms at the A site.

6. In paragraph 5, The above perovskite is characterized by being SnSnO3. A method for producing a stable perovskite material ABO3 containing two valent Sn atoms at the A site.

7. In paragraph 5, Including an additional step of heat treatment at high temperature after the above mist chemical vapor deposition, A method for producing a stable perovskite material ABO3 containing two valent Sn atoms at the A site.

8. In paragraph 4, The above aqueous solution contains a metal ion located at the 4-valent B site. A method for producing a stable perovskite material ABO3 containing two valent Sn atoms at the A site.

9. In paragraph 8, The metal to be located at the above B site is characterized by being at least one of Ti, Sn, Pt, Ce, Pb, Mg, and Hf. A method for producing a stable perovskite material ABO3 containing two valent Sn atoms at the A site.

10. Perovskite compounds represented by the following chemical formulas 1 and 2: [Chemical Formula 1] ABO3 A is a divalent cation Sn or one or more metal ions selected from a divalent cation metal other than the divalent cation Sn, B is one or more metal ions selected from tetravalent cation metals.

11. In paragraph 10, The above perovskite compound is SnSnO3. Perovskite compounds.

12. In paragraph 11, The above perovskite compound is characterized by a band gap of 5.0 eV or more and an optical transmittance of 70% or more in the UV region with a wavelength of 200 nm. Perovskite compounds.

13. In paragraph 10, A or B of the above perovskite compound is characterized in that at least one metal ion among heterogeneous metal ions having an oxidation number between 1+ and 5+ is doped as n-type or p-type. Perovskite compounds.

14. A semiconductor comprising a perovskite compound according to any one of claims 10 to 13.

Images